1. Field of the Invention
The present invention relates to the technical field of level shifters and digital to analog converters and, more particularly, to a decoder level shifter device and a digital to analog converter using the same.
2. Description of Related Art
A voltage level shifter is typically used in changing a low-voltage control signal into a high-voltage control signal. For example, for applying in an LCD device, it typically needs to change a low-voltage digital control signal into a high-voltage control signal in order to drive the TFTs, and thus the voltage level shifter has to be used for proceeding with the voltage level shift.
FIG. 1 is a schematic diagram of a typical decoder level shifter device 100. With the decoder level shifter device 100, when data A[1:0] is inputted, its high and low voltages are indicated by VCC and VSS. After passing through a decoder 110, the decoded signals S0-S3 are generated, and the high and low voltages for the decoded signals S0-S3 are still at VCC and VSS. Next, after passing through four level shifters (LSs) 120, four shifted and decoded signals S0H-S3H, which have high and low voltages VDDA and VSS, are correspondingly generated.
FIG. 2 is a partial circuit of the prior decoder level shifter device 100. From FIG. 2, it is known that the decoder needs at least four decoding circuits 210 to respectively decode the decoded signals S0-S3. One decoding circuit is comprised of at least four transistors, and one level shifter (LS) 120 is comprised of at least four transistors, while there are several transistors required for an inverter. Therefore, one prior decoder level shifter device 100 is comprised of at least 44 transistors, in which the four level shifters 120 have 16 transistors, the four decoding circuits 210 have 16 transistors, and four inverters have 12 transistors. Accordingly, with the decoder 110 and the level shifters 120, the prior art encounters the problem of increased layout area and power consumption. Therefore, it is desirable to provide an improved decoder level shifter device to mitigate and/or obviate the aforementioned problems.